1. Technical Field of the Invention
The present invention relates to a document feeding apparatus which is utilized for use in a copying machine, image reader or microphotographing apparatus for exposing and reading images of an original or for automatically feeding an original to a platen section where photographing is conducted.
2. Related Art
Heretofore, this kind of apparatus has been arranged to automatically feed originals stacked in a document tray one by one by forwarding the uppermost or undermost original stacked in the tray to the platen section. In an apparatus arranged to forward the undermost original as shown in FIG. 1, a pick-up roller b is generally provided at a fixed position under a document tray a and protruding the above the document transport surface c to forward the undermost original along the document transport surface c.
At the next position of the pick-up roller b, a friction pad e and a separation roller f are provided for separating originals transported from the original set section a and forwarding the undermost original. A separation pad g provided between the pick-up roller and the separation section e acts on the upper layer of originals d to obstruct their forward movement.
Originals d are stacked on a document tray a in a bunch with their rear end portion supported by hands and the leading end portion facing the separation roller f in a manner to properly reach the separation roller f sliding on the original transport surface c. At this time, the leading end of originals d softly hits the pick-up roller b protruding on the original transport surface c and override it. In case originals d are flexible, it sometimes happens that the leading end of originals d of the lower layer reaches behind the originals d of the upper layer by obstruction of the pick-up roller b as shown by solid lines in FIG. 1. The same inconvenience also happens when originals d are not arranged properly.
Due to a reason as described above or some other reasons, in case when the undermost original d is forwarded to the separation section e behind the other originals as shown by phantom lines in FIG. 1, the separating and transporting actions affect much on the originals of upper layer than the undermost original and quickly send out one of the originals in the upper layer as illustrated in FIG. 2. On the other hand, however, the undermost original d is forced to pass through the separation section e since the pick-up roller b and separation roller f directly work on the undermost original being left behind. As a result, originals d are transported in overlapping state, which causes paper jam, skew and overlapping transport.
In order to improve the separating operation, it has also been practiced to provide a front separation plate g immediately in front of the separation section e. The front separation plate g is inclined with respect to the transport surface c so as to receive the leading end of a bunch of originals d stored in the original set section a or the originals being forwarded therefrom along the transport surface to subsequently precede the leading end of the undermost original. However, it actually happens sometimes that the originals are forwarded in overlapping state. It may be attributable to the fact that the behind placement of the originals of under layer which occurs when a bunch of originals d is placed in the original tray a can not be solved.